Problem: On planet Larky, 7 ligs = 4 lags, and 9 lags = 20 lugs. How many ligs are equivalent to 80 lugs?
Explanation: Multiply the second equation by 4 to find that 36 lags are equivalent to 80 lugs. Then multiply the first equation by 9 to find that 36 lags are equivalent to 63 ligs. Since each is equivalent to 36 lags, 80 lugs and $\boxed{63}$ ligs are equivalent.